Improvement of the appearance of the skin and slowing down its aging process is achieved using different procedures and technologies. The effect of supplements to eliminate wrinkles, pigmentation unevenness, sun damage and protect the skin from environmental hazards is based on their penetration through the skin. The main obstacle for the penetration of supplements through the skin is the stratum corneum which is only about 50-200 μm thickness. This thin barrier prevents passage of any substance whose size is bigger than a water molecule.
U.S. Pat. Nos. 6,607,508 and 7,025,774 disclose devices and methods for drug delivery by injection, wherein the skin is punctured by a needle and medicine is injected to the required depth. Injections allow for flexible local treatment, direct absorption of the solutions and their delivery to the intercellular fluids by using a minimal substance amount. Disadvantages of such an approach are the sophisticated technique required, the risk of infection, cross-contamination, pain, difficulty of injection depth control, and the danger of harming blood vessels. Another syringe type, the so-called needle-free injector, has the additional drawback that it does not allow for adequate control of the drug injection depth. Such devices are described in “Comparison of a needle free high-pressure injection system with needle-tipped injection of intracavernosal alprostadil for erectile dysfunction”, L. M. Harding, A. Adeniyi, R. Everson, S. Barker, D. J. Ralph and A. P. Baranowski, in International Journal of Impotence Research (2002) 14, 498-501.
U.S. Pat. Nos. 6,652,483, 5,947,928 and 7,226,439 disclose methods and devices for transdermal medicine delivery into the skin. The delivery is controlled by the solutions' physical and chemical parameters: diffusion, solubility and affinity. Diffusion depends on the molecule size. As molecule size decreases, permeability improves. U.S. Pat. No. 7,315,758 proposes additional physical means to increase diffusion, for example, electrical, magnetic and sonar. Transportation of hydrophilic or charged molecules is a particularly difficult process because of the low water content in the stratum corneum which is lipids-based: the skin (epidermis) layer is composed of about 40% lipids, 40% protein and only 20% water. This makes the diffusion method of medicine delivery slow and inefficient.
Delivery of cosmetic and medical solutions via pores could possibly be efficient since pores cover the majority of the skin surface. The pores enable water transfer vital for thermoregulation and for the transfer of the products of metabolism only from the dermis to the surface and not vice versa. These channels contain structured hydrophilic and lipophilic domains that feature exclusively unilateral conductivity toward the outside.
A square millimeter of skin surface contains not less than 3 pores. Pore size depends on pore condition and activity. On average, pore diameter is from 50 to 300 μm. Pores are tubular twisting capillaries that arrive from the depth of the dermis and gradually become cylindrical tubes that open onto the surface of the stratum corneum. The total surface area of pores is less than 1% (0.1% to 1%) of the entire surface area of the skin; hence pores cannot facilitate the delivery of a sufficient amount of material through diffusion. The inventor is not acquainted with methods and devices for delivery of cosmetic and medical solutions via pores that are not based on molecular diffusion.
The delivery of medical or cosmetic solutions through the skin would be facilitated if it were possible to inject solutions directly into the pores.